[Tinyos-2-commits] CVS: tinyos-2.x/doc/txt tep102.txt, 1.1.2.3, 1.1.2.4

[David Gay]

Update of /cvsroot/tinyos/tinyos-2.x/doc/txt
In directory sc8-pr-cvs10.sourceforge.net:/tmp/cvs-serv23910/txt

Modified Files:
      Tag: tinyos-2_0_devel-BRANCH
	tep102.txt 
Log Message:
update for current mica family implementation


Index: tep102.txt
===================================================================
RCS file: /cvsroot/tinyos/tinyos-2.x/doc/txt/Attic/tep102.txt,v
retrieving revision 1.1.2.3
retrieving revision 1.1.2.4
diff -C2 -d -r1.1.2.3 -r1.1.2.4
*** tep102.txt	14 Dec 2005 23:52:36 -0000	1.1.2.3
--- tep102.txt	16 Jun 2006 00:25:58 -0000	1.1.2.4
***************
*** 345,349 ****
  several components::
  
!   configuration CounterPW {
      provides interface Counter<TP, uintW_t>;
    } ... 
--- 345,349 ----
  several components::
  
!   configuration CounterPWC {
      provides interface Counter<TP, uintW_t>;
    } ... 
***************
*** 354,358 ****
  and, except if *W* is 32::
  
!   configuration CounterP32 {
      provides interface Counter<TP, uint32_t>;
    } ... 
--- 354,358 ----
  and, except if *W* is 32::
  
!   configuration CounterP32C {
      provides interface Counter<TP, uint32_t>;
    } ... 
***************
*** 690,697 ****
    } ...
  
! Appendix C: a mote: Mica2 timer subsystem
  ====================================================================
  
! The mica2 HAL exposes its four timers as follows: 
  
  * Timer 0: divides the external 32768Hz crystal by 32 to build AlarmMilli8C
--- 690,710 ----
    } ...
  
! Appendix C: a mote: Mica family timer subsystem
  ====================================================================
  
! Members of the mica family (mica2, mica2dot, micaz) use the Atmega128
! microprocessor and have external crystals at 4 or 7.37MHz. Additionally,
! they can be run from an internal oscillator at 1, 2, 4, or 8 MHz. The
! internal oscillator is less precise, but allows for much faster startup
! from power-down and power-save modes (6 clocks vs 16000 clocks). Finally,
! power consumption is lower at the lower frequencies. 
! 
! The mica family members support operation at all these frequencies via
! a ``MHZ`` preprocessor symbol, which can be defined to 1, 2, 4, or 8.
! If undefined, it defaults to a platform-dependent value (4 for mica2dot,
! 8 for mica2 and micaz).
! 
! The mica family configures its four timers in part based on the value
! of this MHZ symbol:
  
  * Timer 0: divides the external 32768Hz crystal by 32 to build AlarmMilli8C
***************
*** 699,720 ****
    register, these can only be instantiated once.
    Timing accuracy is as good as the external crystal.
! * Timer 1: the internal oscillator is divided by 8 to build AlarmMicro16C
!   and AlarmMicro32C (see Section 3). 3 compare registers are available.
!   The timing accuracy depends on how the mica2 is clocked:
  
!   - internal 8MHz clock: depends on how well the clock is calibrated
    - external 7.37MHz crystal: times will be off by ~8.6%
!   - selecting other clocking options will produce gross inaccuracy
  
! * Timer 2, 3: these timers are not currently exposed by the HAL.
  
! The mica2 HIL components are built as follows:
  
  * TimerMilliC: built using AlarmMilli32C (consuming its single compare
    register)
  * BusyWaitMicroC: implemented using a simple software busy-wait loop which
!   waits for 8 cycles per requested microsecond. Accuracy is the same as
!   with Timer 1.
  
  
- We include here as an example some of the source code for the above components:
--- 712,770 ----
    register, these can only be instantiated once.
    Timing accuracy is as good as the external crystal.
! * Timer 1: the 16-bit hardware timer 1 is set to run at 1MHz if possible.
!   However, the set of dividers for timer 1 is limited to 1, 8,
!   64, 256 and 1024. So, when clocked at 2 or 4MHz, a divider of 1 is
!   selected and timer 1 runs at 2 or 4MHz. To reflect this fact, the 
!   HAL components exposing timer 1 are named ``CounterOne16C`` and
!   ``AlarmOne16C`` (rather than the ``CounterMicro16C`` ``AlarmMicro16C``
!   as suggested in Section 3).
  
!   When building the 32-bit counter and 32-bit alarms, the rate of
!   timer 1 is adjusted in software to 1MHz. Thus the 32-bit HAL components
!   for timer *are* named ``CounterMicro32C`` and ``AlarmMicro32C``.
! 
!   Three compare registers are available on timer1, so up to three instances
!   of ``AlarmOne16C`` and/or ``AlarmMicro32C`` can be created. The timing
!   accuracy depends on how the mote is clocked:
! 
!   - internal clock: depends on how well the clock is calibrated
    - external 7.37MHz crystal: times will be off by ~8.6%
!   - external 4MHz crystal: times will be as accurate as the crystal
! * Timer 2: this timer is not currently exposed by the HAL.
  
! * Timer 3: the 16-bit hardware timer 3 is set to run at a rate close to
!   32768Hz, if possible. As with timer 1, the limited set of dividers makes
!   this impossible at some clock frequencies, so the 16-bit timer 3 HAL
!   components are named ``CounterThree16C`` and ``AlarmThree16C``. As 
!   with timer 1, the rate of timer 3 is adjusted in software when
!   building the 32-bit counter and 32-bit alarms, giving components
!   ``Counter32khz32C`` and ``Alarm32khz32C``. As with timer 1, three compare
!   registers, hence up to three instances of ``Alarm32khz32C`` and/or
!   ``AlarmThree16C`` are available.
  
!   At 1, 2, 4 and 8MHz, ``Counter32khz32C`` and ``Alarm32khz32C`` run
!   at 31.25kHz (plus clock rate inaccuracy). At 7.37MHz, they run at
!   ~28.8kHz.
! 
! When an Atmega128 is in any power-saving mode, hardware timers 1, 2 and 3
! stop counting. The default Atmega128 power management *will* enter these
! power-saving modes even when timers 1 and 3 are enabled, so time as
! measured by timers 1 and 3 does *not* represent real time.  However, if any
! alarms built on timers 1 or 3 are active, the Atmega128 power management
! will not enter power-saving modes.
! 
! The mica family HIL components are built as follows:
  
  * TimerMilliC: built using AlarmMilli32C (consuming its single compare
    register)
  * BusyWaitMicroC: implemented using a simple software busy-wait loop which
!   waits for ``MHZ`` cycles per requested microsecond. Accuracy is the same as
!   Timer 1.
  
+ Finally, the mica family motes measure their clock rate at boot time, based
+ on the external 32768Hz crystal. The results of this clock rate measurement
+ are made available via the ``cyclesPerJiffy`` command of the
+ ``Atm128Calibrate`` interface of the ``MeasureClockC`` component. This
+ command reports the number of cycles per 1/32768s. Please see this interface
+ definition for other useful commands for more accurate timing.